EP 0868072 A3 19990818 - Shading correction for an image scanner
Title (en)
Shading correction for an image scanner
Title (de)
Schattierungskorrektur für einen Bildscanner
Title (fr)
Correction de l'effect d'ombre pour un scanner d'image
Publication
Application
Priority
- JP 7625097 A 19970327
- JP 8424097 A 19970402
- JP 206398 A 19980108
- JP 206498 A 19980108
Abstract (en)
[origin: EP0868072A2] An image reading apparatus includes: a line sensor 5 for converting light from an original into an electric signal; an A/D converting unit 12 for converting the electric signal derived from the line sensor 5 into a digital signal; a white reference storage unit 24 for storing white reference data set before the original is read; a black reference storage unit 22 for storing black reference data set before the original is read; a light-source light amount detecting unit for detecting a light amount of a light source; and a shading correcting unit 13 for shading-correcting an output signal derived from the A/D converting unit 12 with employment of both white reference data corrected by a white reference correction coefficient and the black reference data. As a consequence, the shading corrections can be performed along both a main scanning direction and a sub-scanning direction. Also, an image reading method includes: a) a step for detecting and setting sub-scanning white reference data when white reference data used in a shading correction is set; b) a step for detecting sub-scanning white reference data in each of reading lines; c) a step for setting as a white reference correction coefficient a ratio of a difference between the sub-scanning white reference data when said white reference data is set and black reference data to another difference between said sub-scanning white reference data in the respective reading lines and said black reference data; and d) a step for reading the original while executing a shading correction with employment of white reference data corrected by the white reference correction coefficient. In this image reading method, in the case where a plurality of the originals are read, the above-described steps b), c), and d) are repeatedly performed. As a result, since the setting operation for setting again the white reference data can be omitted, the time period required to read the image can be shortened. <IMAGE>
IPC 1-7
IPC 8 full level
H04N 1/401 (2006.01)
CPC (source: EP US)
H04N 1/401 (2013.01 - EP US)
Citation (search report)
- [XA] DE 4020817 A1 19910110 - TOSHIBA KAWASAKI KK [JP]
- [A] EP 0439358 A2 19910731 - HEWLETT PACKARD CO [US]
- [A] EP 0439357 A2 19910731 - HEWLETT PACKARD CO [US]
- [A] GB 2110899 A 19830622 - XEROX CORP
- [A] US 5151796 A 19920929 - ITO YASUO [JP], et al
- [A] EP 0552849 A2 19930728 - CANON KK [JP]
Designated contracting state (EPC)
AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
DOCDB simple family (publication)
EP 0868072 A2 19980930; EP 0868072 A3 19990818; EP 0868072 B1 20050112; DE 69828542 D1 20050217; DE 69828542 T2 20051222; US 6151419 A 20001121
DOCDB simple family (application)
EP 98105641 A 19980327; DE 69828542 T 19980327; US 4878698 A 19980327